Utilizing Large-Scale Structure to Constrain Unstable Dark Matter
Wang, Mei-Yu (Department of Physics & Astronomy, University of Pittsburgh)

We study the effects of decaying dark matter on large-scale structure and the ability of forthcoming experiments to probe interesting models of unstable dark matter. Here we consider two types of decay model. In one scenario dark matter decay into two non-interacting relativistic particles. In the second type of model dark matter decays into a slightly less massive, but stable, dark matter particle accompanied by a relativistic daughter particle. We solve for the linear perturbative evolution of the matter power spectrum and the spectra of the metric potentials. In addition, we implement a number of corrections to account for nonlinear evolution on relevant scales. We then proceed to study the imprint of unstable dark matter on the galaxy and lensing power spectra. In the next decade weak gravitational lensing will become a powerful tool for studying cosmology as future large imaging survey like DES, LSST, Euclid, and WFIRST provide data of unprecedented utility. We show that weak lensing shear correlations will provide restrictive constraints on the lifetime or fraction of unstable dark matter. Indeed we show that such constraints should compete with limits from other techniques even under pessimistic assumptions about the utility of the survey data and the progress of theoretical modeling. In more optimistic scenarios, we show that lensing shear correlations will likely provide the strongest, model-independent constraints on unstable dark matter while simultaneously providing the sought-after, percent-level constraints on the dark energy equation of state, and strong constraints on neutrino mass.